Process for the preparation of 2-aryloxyethyl carboxylates

ABSTRACT

A PROCESS FOR THE PREPARATION OF 2-ARYLOXYETHYL ESTERS FROM AN ARYL ESTER PREPARED FROM A PHENOLIC COMPOUND AND AN ACID SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC, CYCLOALIPHATIC AND AROMATIC MONO- AND POLY-CARBOXYLIC ACIDS, AND SAID ARYL ESTERS SUBSTITUTED IN THE ARYL RESIDUE WITH AT LEAST ONE HALOGEN AND/OR ALKYL GROUP, WHICH COMPRISES REACTING SAID ARYL ESTER WITH ETHYLENE CARBONATE IN APPROXIMATELY EQUIVALENT AMOUNTS AT A TEMPERATURE OF ABOUT 100 TO 200*C. AND IN THE PRESENCE OF A CATALYST.

United States Patent 3,557,167 PROCESS FOR THE PREPARATION OF Z-ARYLOXYETHYL CARBOXYLATES Hans-Leo Hiilsmann, Witten-Rudinghausen, and Gustav Renckhotf, Witten, Ruhr, Germany, assignors to Dynamit Nobel AG Werk Witten, Witten, Germany N0 Drawing. Filed Apr. 26, 1968, Ser. No. 724,630 Claims priority, applicatior; gGermany, Apr. 27, 1967,

Int. Cl. C11c 3/(30; C07c 69/78 U.S. Cl. 260-4105 13 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of uniform Z-aryloxyethyl esters of aliphatic, cycloaliphatic or aromatic carboxylic acids. More particularly, the present invention is concerned with a process for the preparation of 2-aryloxyethyl esters from aryl esters of mono-, aliphatic, cycloaliphatic or aromatic carboxylic acids and the aryl esters of poly-, aliphatic, cycloaliphatic 0r aromatic carboxylic acids. The process of the present invention is also effective and relates to the preparation of mixed alkyl aryl esters of said acids.

Heretofore, the production of mixed monoalkyl-mono- 2-aryloxyethyl esters of dibasic acids was possible only by reacting monoalkyl ester monoacid halogenides with the oxyethylation products from phenols and ethylene oxide. In accordance with the process of the present invention, operating with the highly reactive and strongly corrosive monoester chlorides is avoided.

SUMMARY OF THE INVENTION An object of the present invention is to avoid the prior art disadvantages in the preparation of Z-aryloxyethyl carboxylates.

Another object of the present invention is to provide an improved process for the preparation of Z-aryloxyethyl esters of aliphatic, cycloaliphatic or aromatic carboxylic acids which may be carried out in an eflicacious and economical manner.

A further object of the present invention is to pro vide a process for preparation of Z-aryloxyethyl carboxylates in high yields.

Other objects and further scope of applicability of the present invention wiH become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Pursuant to the present invention, it has been found that the above-mentioned disadvantages may be eliminated and a much improved process for the preparation of Z-aryloxyethyl esters of aliphatic, cycloaliphatic or aromatic carboxylic acids can be obtained by reacting the aryl esters of these acids with ethylene carbonate at temperatures of about to 200 C. in the presence of an ester radical interchange catalyst. The reaction takes place in accordance with the following equation:

Suitable starting materials for the process of the present invention are the aryl esters of monoaliphatic, cycloaliphatic or aromatic carboxylic acids and the aryl esters of poly-, aliphatic, cycloaliphatic or aromatic carboxylic acids. In addition, the aryl esters which are substituted in the aryl residue by one or more than one halogen and/ or alkyl groups, such as for example, cresol esters or the isomeric monoor dichlorophenyl esters, can also be used. The preferred aryl esters are the phenyl esters or the phenyl esters which are substituted in the phenyl residue by one or more than one halogen and/or alkyl group.

When reacting mixed alkylaryl esters of dicarboxylic acids with ethylene carbonate, only the aryl ester group reacts, whereas the alkyl ester group remains intact. The reaction takes place in the following manner:

The aliphatic carboxylic acids which can be used to produce the aryl ester starting materials of the present invention include the aliphatic carboxylic acids having about 2 to 18 carbon atoms, such as for example, acetic acid, butyric acid, lauric acid, stearic acid, succinic acid, sebacic acid and other like acids. The cycloaliphatic carboxylic acids include cyclohexane monocarboxylic acid, cyclohexane dicarboxylic acid, hexahydrobenzoic acid and the like. The aromatic carboxylic acids which can be effectively used to produce the aryl esters used in the present process comprises acids such as benzoic acid, isomeric toluic acids, terephthalic acid, hexahydroterephthalic acid, chloroterephthalic acid, dichloroterephthalic acid, isophthalic acid, diphenyl dicarboxylic acids, diphenylmethane dicarboxylic acids, benzophenone dicarboxylic acids, trimesic acid, naphthalene dicarboxylic acids, etc.

As the phenolic components which can be used to react with the above acids to produce the aryl ester starting materials of the present process, the monohydric phenols or naphthols can be mentioned including those which are substituted in the aryl residue by one or more than one halogen and/ or alkyl group. Suitable phenolic compounds include for example phenol, the isomeric cresols or xylenols, butylphenols, octylphenols, benzylphenols, chlorophenol, dichlorophenol, chloro-methylphenol, fi-naphthol, etc. Instead of pure phenols it is also possible to employ technical isomeric mixtures such as those commercially available on the market. In the latter case, mixed aryl esters are obtained.

The reaction is generally conducted at a temperature of about 100 to 200 C. Preferably a temperature of about to C. is maintained, at which temperatures the reaction proceeds rapidly without there being any major deposition of the ethylene carbonate.

The reaction is catalyzed by a number of salts. Very effective are the halides or hydroxides of the alkali and alkaline earth metals, particularly lithium chloride or calcium chloride. In addition, rhodanides for example potassium rhodanide are also useful. Furthermore, salts of organic basis, such as for example, tetramethylammonium chloride or guanidine rhodanide are also suitable catalysts for the process of the present invention. These catalytically active materials are employed in amounts of about 0.5 to 20% by weight, based on the amount of the aryl ester utilized. The reaction time is dependent upon the concentration of the catalysts employed. For example in the presence of 1% by weight of the above-mentioned catalysts, approximately 20 hours of reaction time is utilized. In the presence of about 10% by weight of the above catalyst the reaction can be terminated in most cases within about 2 to 5 hours.

The separation of the reaction products from the catalysts is readily accomplished when using inorganic salts, since these salts are present in the solid phase after the reaction is terminated. The aryloxyethyl esters can be separated from catalysts soluble in the reaction mixture, such as for example, the salts of organic basis, in accordance with conventional methods, such as the distillation of the reaction substance under vacuum or recrystallization from solvents, preferabl from hydrocarbons. In this manner the product can be obtained in a substantially pure form.

The process of the present invention for the preparation of 2-aryloxyethyl carbonates exhibits substantial advantages when compared to the conventional processes. Previously, the esterification of carboxylic acids with 2- aryloxyethanols, the latter being obtained from phenols by oxyethylation by means of ethylene oxide, had to be utilized for the production of aryloxyethyl esters. During this reaction, higher oxyethylated phenols are produced as by-products and these phenols can only be separated from the reaction mixture with great difliculty. The novel way of preparing 2-aryloxyethy1 carboxylates according to the present invention exhibits the advantage that the formation of esters of the general formula wherein n is a number larger than 1 is prevented.

Heretofore, the production of mixed monoalkyl-mono- 2-aryloxyethyl esters of dibasic acids was possible only by reacting monoalkyl ester monoacid halogenides with the oxyethylation products from phenols and ethylene oxide. In accordance with the process of the present invention utilization of the highly reactive and strongly corrosive monoester chlorides is avoided.

Approximately equivalent amount of reactants are employed in the reaction of the present invention. By equivalent amounts is meant the number of groups on the reactants which take part in the reaction. Thus, for example an equivalent amount of ethylene carbonate is used for each respective reactive group of the ester employed. If desired, a small excess, for example a few percent above the equivalent amount of ethylene carbonate can be employed in order to compensate for minor losses of the latter by thermal decomposition.

The 2-aryloxyethyl esters prepared in accordance with the process of the present invention are normally obtained in almost quantitative yields. They are very effective as plasticizers for synthetic materials and intermediates for use in organic synthesis.

The following examples are given merely as illustrative of the present invention and are not to be considered as limiting.

EXAMPLE 1 136 parts by weight of phenyl acetate (1 mol) is mixed with 88 parts by weight of ethylene carbonate (1 mol), and is heated with stirring to 150 C. in the presence of 1.3 6 parts by weight (1% by weight) of tetramethylammonium chloride, based on the acetic acid phenyl ester employed. After about 2.5 hours the evolution of carbon dioxide terminates. 180 parts by weight of phenoxyethyl acetate, obtained in a quantitative yield, is recovered during the vacuum distillation at a temperature of about 131-- 4 132 C. and a pressure of 15 mm. Hg. The saponification number of the ester is 312 (calculated: 311).

EXAMPLE 2 138 parts by weight of phenyl laurate (0.5 mol) is mixed with 44 parts by weight of ethylene carbonate (0.5 mol) and heated to 150 C. in the presence of 1.4 parts by weight of tetramethylammonium chloride (1% by weight, based upon the ester employed). The reaction is terminated after about 3.25 hours. The yield of phenoxyethyl laurate is 159 parts by weight, corresponding to 99.5% of the theoretical yield. The saponification number of the ester is 175.5 (calculated: 175.5). The ester melted at 35.5 to 36.0 C.

EXAMPLE 3 180 parts by weight of phenyl stearate (0.5 mol) is reacted as in Example 2 with 44.9 parts by Weight of ethylene carbonate (0.51 mol) with the addition of 1.8 parts by weight of lithium chloride. The yield of phenoxyethyl stearate is 200 parts by weight (calculated: 202), corresponding to 99% of the theoretical yield. The saponification number of the ester is 139 (calculated: 139) and the melting point is about 55 C.

EXAMPLE 4 parts by weight of phenyl hexahydrobenzoate (0.5 mol) is reacted with 44 parts by weight of ethylene carbonate (0.5 mol) with the addition of 0.9 part by weight of tetramethylammonium chloride at 150 C. for about 2 hours. There is obtained parts by weight of phenoxyethyl hexahydrobenzoate, corresponding to about 93% of the theoretical recovery. The saponification number of the ester is 136.

EXAMPLE 5 138 parts by weight of di-m-cresyl cyclohexanedicarboxylate (0.31 mol) is reacted with 69 parts by weight of ethylene carbonate (0.78 mol) at about C. with stirring using 1.4 parts by weight of lithium chloride as the catalyst. After 21.5 hours of reaction time the evolution of carbon dioxide is terminated. The product, di-(m-cresyloxyethyl)-cyclohexanedicarboxylate, obtained in a quantitative yield, is recrystallized from petroleum ether. The reaction product melted at 95 C. and exhibited a saponification number of 248 (calculated: 255).

'EXAMPLE 6 99 parts by weight of phenyl benzoate (0.5 mol) is heated with stirring to C. with 44.9 parts by weight of ethylene carbonate (0.51 mol) together with 10 parts by weight of lithium chloride. After 5 hours of reaction time, the evolution of carbon dioxide is terminated. After removing the salt, 118 parts by weight of pure phenoxyethyl benzoate is obtained by distillation under a vacuum at a temperature of about 143 to 148 C. and a pressure of about 0.4 mm. Hg, corresponding to 97.5% of the theoretical recovery. The saponification number of the ester is 237 (calculated: 232). The melting point is 58 C.

EXAMPLE 7 Example 6 is repeated with the addition of 1% by weight of calcium chloride instead of lithium chloride. Phenoxyethyl benzoate is recovered in an 81% yield. The saponification number of the ester is 235 (calculated: 232). The melting point is 58 C.

EXAMPLE 8 212 parts by weight of m-cresyl benzoate (1 mol) is heated with 88 parts by weight of ethylene carbonate (1 mol) with stirring at 150 C. As the catalyst, 1% by weight of lithium chloride, based on the weight of the cresol ester, is employed. After 18.5 hours, the reaction mixture is distilled. Pure m-cresyloxyethyl benzoate is recovered at a temperature of 153 to 154 C. and a pressure of 0.4 mm. Hg. The ester is liquid at room temperature. The yield is 87% of the theoretical yield.

EXAMPLE 9 106 parts by weight of phenyl p-toluate is reacted with 44.9 parts by weight of ethylene carbonate. The phenoxyethyl p-toluate is obtained in a pure form by distillation under vacuum at a temperature of about 165 to 170 C. and a pressure of about 0.4 mm. Hg. As the catalyst, 1% by weight of lithium chloride, based on the weight of the phenyl ester, is employed. 122 parts by weight of the ester is distilled, giving a yield corresponding to 97% of the theoretical yield. The saponification number is 224 (calculated: 219). The melting point is about 45 to 46 C.

EXAMPLE 10 Example 9 is repeated, the catalyst used being 1% by weight of tetramethylammonium chloride. The reaction lasted 1.5 hours. The yield of phenoxyethyl l-toluate is 97% of the theoretical yield and the saponification number is 222.5 (calculated: 219). The ester melted at a temperature of about 44 to 45 .5" C.

EXAMPLE 11 Example 9 is repeated using 1 part by weight of potassium hydroxide as the catalyst in place of lithium chloride. After a reaction time of 2 hours a yield of 125 parts by weight of phenoxyethyl l-toluate is recovered. This represents 99.5% of the theoretical recovery. The saponification number is 223 (calculated: 219).

EXAMPLE 12 79.5 parts by weight of diphenyl isophthalate (0.25 mol) is reacted with 44 parts by weight of ethylene carbonate (0.5 mol) at a temperature of 150 C. and in the presence of 7.95 parts by weight of lithium chloride as the catalyst therefor. The reaction is terminated after 2.5 hours resulting in the production of 100 parts by weight of di-(phenoxyethyl)-isophthalate, corresponding to a 98% recovery of the theoretical yield. The saponifi cation number of the ester is 276.5 (calculated: 276).

EXAMPLE 13 79.5 parts by weight of diphenyl terephthalate (0.25 mol) is reacted with 66 parts by weight of ethylene carbonate (0.75 mol) at a temperature of 170 C. and in the presence of 1% by weight of lithium chloride, based on the weight of the diphenyl terephthalate. After distilling 01? the excess ethylene carbonate, 100 parts by weight of di-(phenoxyethyl)-terephthalate is recovered. The ester is recrystallized from benzene. The saponification number is 275 (calculated: 276) and the melting point is about 100 to 101 C.

EXAMPLE 14 86.5 parts by weight of di-m-cresyl isophthalate (0.25 mol) is reacted with 44.9 parts by weight of ethylene carbonate (0.51 mol) at a temperature of 150 C. and in the presence of 1% by weight of lithium chloride, based on the weight of the di-m-cresyl isophthalate. After 22.5 hours the reaction is terminated. The reaction product is dissolved in xylene, the solution is then treated with activated charcoal and the solvent is again removed. 95 parts by weight of di-(m-cresyloxyethyl)-isophthalate is obtained which represents a recovery of about 88% of the theoretical recovery. The saponification number of the ester which is liquid at room temperature is 261.5 (calculated: 258).

EXAMPLE 15 A mixture of 96.8 parts by weight of di-p-chlorophenyl terephthalate (0.25 mol), 44 parts by weight of ethylene carbonate (0.5 mol) and 1 part by weight of lithium chloride is heated for 16 hours with stirring at a temperature of 150 C. After the period of time has elapsed, the carbon dioxide evolution is complete. The reaction product is recrystallized from petroleum ether. 116.7 parts by weight of di-(p-chlorophenoxyethyl)-terephthalate with a melting point of 148 C. is recovered. The yield corresponds to 98.5% of the theoretical yield. The saponification number of the ester is 236 (calculated: 235.5).

EXAMPLE 16 128 parts by weight of monomethylmonophenyl terephthalate (0.5 mol) is heated for 1.75 hours at a temperature of 150 C. with 44 parts by weight of ethylene carbonate (0.5 mol) and 12.8 parts by weight of lithium chloride as the catalyst. The monomethylphenoxyethyl terephthalate is obtained in a quantitative yield. The saponification number of the mixed ester is 375 (calculated: 373).

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications are intended to be included within the scope of the following claims.

It is claimed:

1. A process for the preparation of 2-aryloxyethyl esters from an aryl ester prepared from a phenolic compound and an acid selected from the group consisting of aliphatic, cycloaliphatic and aromatic monoand polycarboxylic acids, and said aryl esters substituted in the aryl residue with at least one halogen and/ or alkyl group, which comprises reacting said aryl ester with ethylene carbonate in approximately equivalent amounts at a temperature of about to 200 C. and in the presence of a catalyst selected from the group consisting of the halides, hydroxides and rhodanides of the alkali and alkaline earth metals and salts of 'organic bases.

2. The process of claim 1, wherein the catalyst is present in an amount of about 0.50 to 20% by weight based on the amount of the aryl ester utilized.

3. The process of claim 1, wherein the reaction is conducted at a temperature of about to C.

4. A process for the preparation of 2-aryloxyethyl carboxylates from an aryl ester prepared from a phenolic compound selected from the group consisting of monohydric unsubstituted-, alkyl substitutedand benzyl substituted-phenols, monohydric naphthols and mixtures thereof and an acid selected from the group consisting of aliphatic, cycloaliphatic and aromatic monoand polycarboxylic acids, and said aryl esters substituted in the aryl residue with at least one halogen and/ or alkyl group, which comprises reacting said aryl ester with ethylene carbonate in approximately equivalent amounts at a temperature of about 100 to 200 C. and in the presence of an effective amount of a reaction catalyst selected from the group consisting of the halides, hydroxides and rhodanides of the alkali and alkaline earth metals and salts of organic bases.

5. The process of claim 4, wherein a small excess amount of ethylene carbonate is utilized.

6. The process of claim 4, wherein the aryl esters are mixed alkylaryl esters of aromatic dicarboxylic acids.

7. The process of claim 4, wherein the aryl ester is selected from the group consisting of phenyl acetate, phenyl laurate and phenyl stearate.

8. The process of claim 4, wherein the aryl ester is selected from the group consisting of phenyl hexahydrobenzoate, di-m-cresyl cyclohexanedicarboxylate, phenyl benzoate, m-cresol benzoate, and phenyl p-toluate.

9. The process of claim 4, wherein the aryl ester is selected from the group consisting of diphenyl isophthalate, diphenyl terephthalate, di-m-cresyl isophthalate, dip-chlorophenyl terephthalate, and monomethylmonophenyl terephthalate.

10. The process of claim 4, wherein the catalyst is selected from the group consisting of tetramethylammonium chloride, lithium chloride, and calcium chloride.

11. The process of claim 4, wherein the reaction is carried out under a vacuum.

12. The process of claim 4, wherein the recovery of the 2-aryloxyethyl carboxylate is carried out by distillation.

13. The process of claim 4, wherein the recovery of the Z-aryloxyethyl carboxylate is carried out by crystallization.

8 References Cited UNITED STATES PATENTS 2,448,767 9/1948 Carlson 260-491 3,256,305 6/1966 Van Gyzen 260-476 US. 01. X.R. 260-468, 469, 475, 476, 485, 491 

